Ground deformation occurring in the Greater Vancouver region, British Columbia, from twenty years of ERS-ENVISAT-RADARSAT-2 InSAR observations

Abstract

Ground subsidence in the south-western part of British Columbia, the third largest metropolitan area in Canada with over 2.2 millions of inhabitants, was measured using the Multidimensional Small Baseline Subset (MSBAS) advanced Differential Interferometric Synthetic Aperture Radar (DInSAR). The MSBAS (Samsonov and d'Oreye, 2012) software calculates two dimensional time series of ground deformation from multiple DInSAR data sets acquired with various acquisition parameters (e.g. spatial and temporal resolution and coverage, wavelength, azimuth and incidence angles). The two dimensional time series produced here have improved temporal resolution, almost uninterrupted coverage and lower noise. The Synthetic Aperture Radar (SAR) data used in this study consists of seven independent sets: one ascending and one descending ERS-1/2 and ENVISAT frames, together spanning July 1995 - September 2010, and three RADARSAT-2 frames spanning February 2009 - October 2012. During the July 1995 period October 2012 we observed fast ground subsidence with a maximum rate greater than -2 cm/year in the Greater Vancouver region that includes the Fraser River delta and the cities of Burnbary, Richmond, Surrey, and Vancouver. The fastest subsidence was observed beneath the Vancouver International Airport and around agricultural and industrial regions. Rapid sub-centimeter ground deformation also occurred during the summer and fall of 2009-2012. These time series suggest that the subsidence rate at the studied regions does not decrease with time as suggested in previous studies but actually increases. The long term impact of subsidence on infrastructure can be significant and needs to be investigated further.